// Used to link graphs contained in TF_WhileParams to the parent graph that
  // will eventually contain the full while loop.
  TF_Graph* parent;
  TF_Output* parent_inputs;
};

struct TF_OperationDescription {
  TF_OperationDescription(TF_Graph* g, const char* op_type,
                          const char* node_name)
      : node_builder(node_name, op_type, g->graph.op_registry()), graph(g) {}

    TF_AddInputList(desc_, inputs, TF_ARRAYSIZE(inputs));
  }

  ~CApiColocationTest() override {
    TF_DeleteGraph(graph_);
    TF_DeleteStatus(s_);
  }

  void SetViaStringList(TF_OperationDescription* desc,
                        const std::vector<std::string>& list) {
    std::unique_ptr<const void*[]> list_ptrs;
    std::unique_ptr<size_t[]> list_lens;
    StringVectorToArrays(list, &list_ptrs, &list_lens);

  // one cannot call ASSERT_* methods in non-void-returning functions (when
  // exceptions are disabled during compilation)
  void UseHelper(const std::vector<TF_Output>& inputs, TF_Operation** op) {
    TF_OperationDescription* desc =
        TF_NewOperation(host_graph_, func_name_, func_node_name_);
    for (auto input : inputs) {
      TF_AddInput(desc, input);
    }